How to check for unread email

var
    Inbox: MAPIFolder;
    NewMail: boolean;
  ...
    Inbox := NmSpace.GetDefaultFolder(olFolderInbox);
    NewMail := (Inbox.UnreadItemCount > 0);
    if NewMail then
      ShowMessage(Format('Unread items in Inbox: %d', [Inbox.UnreadItemCount]));

The constant olFolderInbox is defined in Outlook_TLB as $00000006.